Slip rings on induction motors



April 2 1924. 1,491,957

R; KIMURA SLI-P RINGS oN INDUCTION MOTORS Filed May 8, 1920 2 sheets-sheer 1 Elf? INVENTOR.

April 29, 1924. 1,491,957

. y R. KIMURA A sLIPRINs oN INDCTION MOTORS Filed May 8, 1920 2. sheetewsheeyz l A INVENToR.

i By 76mm@ @WAHM/vasi d: L

Patente-d Apr. 29, 1924.

' .l UNiiEosTATEs l l l 1,491,957 PATENT OFFICE.

aYoJIRo KIMURA, or 'roBAcHo SHIMAGUN MIEKEN, JAPAN, AssIGNoR To THETOBA y nENxI sEIsAxUsno, oFsIIIMAoUN MIEKEN, JAPAN, A CORPORATION or JAPAN.

' SLIP RINGS oN INDUCTION MOTORS.

Application lfiled May 8, 1920. Serial No. 379,941..

To llwhom tmay concern.'

Be' it known that I,A RYOJIRO, K IMURA, residing at No. 789 Tobachov Shimagun Mieken, J apan, have invented new and useful Improvements in Slip Rings on Induction Motors (for which I have filed an application in the Japanese Empire AprillO, 1919, No. 45,7 60,), of which the following is `a specification. 'f n n My -invention relates to slip rings for, induction motors; and the object' thereof is effectually to prevent sparks andreduce cost by simplifying the construction. f n

It consists `in various features rand ycornbinations hereinafter` describedk and more particularly claimed, reference being had to the accompanying drawings forming a part ofv this specification, in which, f Fig. l is a view in section, on several shaft beinga section on the Aline AO; the

part below thereofa section on the line OJ and the brush holder bracket, a. section on thel line OB, all on Fig. 2; V o

Fig..2 yalso is ar view'in section, the left half being a 'section on the line DEFG and the right halfy that lon the line HI, ofy Fig. 1;

Fig. 3 isa sectional elevation of the. arm wheel with slip rings; l y Fig. 4 is a plan-of the whole; f i

Figs.f5 andare, respectively, fronty and sideelevations of the brushholder; and

Fig. 7 .is-a circuit diagram. o l The same reference numbers represent the same or corresponding parts throughout all Vthe figures., y

Accordingto my shaft 1, on one' side of the rotor, vis keyed a wheel having radial armsi2. To the/arms y2 arefixedk byk means of set screws 5, 5' two concentric slip rings/4,14' with insulators 6 betweenthearnis, rings, and heads of the set screws y5, 5 and the arms 2 having holes 16, thru which the said set screws pass,.tlie hole being larger than the screw so that tlie screws do nottouch the arms. In this way the slip rings are perfectly insulated from the arms 2. To'tlie slip ring 4 is firmly fixed a pair of L-shaped short circuit leads 7; and to the slip ring 4', another pair of short circuit leads 7 of a similar shape but with shorter legs, respectively, by means of set screws 8 and 8'.

On the main shaftyl, is keyed ya shift collar 11 in such a way that the collar can planes,'the part above the axis of .the main on each side.

invention yon the main slide backward and forward on the shaft. To theshift collar 11 are fixed twopairs Of short circuit tongues 9, 9' arranged in such a way that they can be brought to contact` respectively with the short circuit leads y7 an 7 a groove 10 which engages two legs 19 of a brush holder bracket 18 to be described later on.y Each of theseklegs has a pin 17 on the outside, which engages the free end of one of two' levers 13, the other end of which is firmly fixed to a shaft 21 which is rocked by a handle 20 supported by a bracketl firmly fixed to the bearing 14 of the motor. yThus by working the liandle20 the shift collar 11 maybe made toy slide on the shaft to and fro through the levers 13 and the pins 17, and consequently the shortl circuit tongues 9, 9 also moved backward and forward. In Fig. 1, in full lines, the shiftcollarll is shown at The shift collar 11 is provided withr onev ofitsv extreme positions when' the short circuittongues 9, 9' are whollyout of contact with thesliort circuit leads 7, 7'; and the dotted lines in the'same' figure show the shift collar atl the otherl extreme position when the tonguesl are *in contact with the leads.

The brushholder vbracket 18has la sym-` metrical construction and is shaped something like-a saddle, having two legs 19, one

its upper lpart the saidbracket slides on, guide rods 22 firmlyl fixed tothe bearing 14.A

Thuis, ifthe handleis moved one way or the other the brush holder bracket slides to `and fro onV the guide-rods 22 at theVV same time causing the shift collar 11y to slide correspondingly on the main shaft 1. A

y.On each side of the brushholder bracket 18 are attached two brush holders 23, 23', respectively supporting brushes 25, 25', the said brush holders being secured to the said bracket, as is shown in Figs. 5 and 6, by bolt 24, with an insulator between them. Brushes 25, 25 have each a hole into which is inserted a projecting rod 26. Each of the brushes 25, 25 at one end is engaged by a spiral spring 29 provided in a spring holder 28, and it is thereby pressed in contact with the slip ring. The brushes 25 bear against ring 4 and the brushes 25' against the ring 4.

.The legs 419 `of thebrush:

The wire connection, as is shown in the diagram is as follows: the wires (a) and (o) connect the windings of the rotor with the slip rings 4, 4', the wires (d) and (e) connect the slip ring 4, 4' with the. rheostat 30, (c) is connected to the main shaft l, utilizing the said shaft as a lead wire, and the wire (7') connects the brush holder bracket 18, which has electrical connection with the main shaft, with the rheostat.

The operation is as follows: lVith the parts in the position they occupy when the short circuit tongues are disconnected from the short circuit leads, as shown in full lines in Fig. l, and the brushes, 25 and 25', in contact with the respective slip rings, 4 and 4', three phase alternating current is sent to the stator winding, and as a result ofthe revolving field set np by the stator current, current is induced in the secondary which flows in one phase to the rheostat, through the lead wire (c t), slip ring 4, brush 25 and lead wire (d), in the second phase through the lead wire (b), slip ring 4', brush 25' and lead wire (6); andin lthe third phase through the main shaft (lead wire c), brush holder bracket 18 and lead wire (f). Then, remove all the resistance by moving the handle towards the position shown by dotted lines, the short circuit tongues gradually approaching the leads 7, 7' and effecting contact therewit-h. At that time, however, the brushes 25, 25' are still in contact with the slip rings 4, 4. On continuing the movement of the handle the short circuit tongues move further towards the short circuit leads, until the whole surfaces of the two come into contact. At that moment the bottom of the slot 27 provided in the brush holder strikes against the projecting rod 26 and disconnects the brushes 25, 25 from the slip rings 4, 4.-'.

The main features of this invention consist in arranging the parts in such a way that the brushes and the short circuit tongues move always in the same direction, that the brushes move into or out of contact with the slip rings perpendicular-ly and in a straight line motion, and that the short circuiting is effected before the brushes are out of contact with the slip rings. Unlike slip rings hitherto used, in my invention the surface of the slip rings and that of the brushes make no angle with each other in moving into or out of contact, the whole surface contact is broken all at once in disconnecting as the brushes are maintained in perfect contact until short circuiting is completely effected. I thus minimize the wear of leads and prolong their life. Moreover, as the mechanism is very simple the first cost is low and the repair is easy.

Having thus described my invention, what I claim is:

l. The combination, in an induction motor, of a pair of rings; two sets of short circuit leads having their ends parallel to the main shaft, two sets of brushes movable into and out of contact with said rings: a pair of short circuit tongues movable into and out of contact with said short circuit leads; and a bracket on which said brushes and said tongues are mounted, whereby they move in the same direction.

2. The combination, in an induction motor, of a pair of rings; two pairs of Ashort circuit leads havin their ends parallel to the main shaft; siort circuit tongues; a shift collar to which said tongues are secured; two sets of brushes; a brush holder bracket on said collar; and a handle for sliding collar on the main shaft.

3. The combination, in an induction motor, of slip ring; brushes for the respective rings, short circuit leads, tongues for the 1x spective leads, said brushes and tongues being mounted for movement parallel with the motor axis and in the same direction in effecting short circuiting, and means to maintain thebrushes in closing position until after the tongues and leads are in Contact.

4. An induction motor having slip rings, and coacting brushes, short circuiting means comprising shiftable tongues, said tongues and brushes moving in the same direction, means for supporting the brushes to move parallel with the motor shaft. axis and in a direction perpendicular to the plane of the contact surfaces of the rings, the tongues also being carried by said support, and means for moving the brushes after the tongues reach circuit-closin g position.

This 22nd day of March, 1920.

RYOJIRO KIMURA. 

